doc: make doc testable

doc/_readme/scripts/run.sh

@@ -0,0 +1,10 @@
+#!/bin/bash
+cd ./doc/_readme/ || exit 1
+llgo build -v ./...
+pip3 install --user numpy
+for dir in ./*/; do
+  if grep -q "func main()" "$dir"/*.go 2>/dev/null; then
+    echo "Running examples in $dir"
+    llgo run "$dir"
+  fi
+done